Suffering, often as a means of redemption, is a recurrent theme in Russian literature. Fyodor Dostoyevskyin particular is noted for exploring suffering in works such as Notes from Underground and Crime and Punishment. Christianity and Christian symbolism are also important themes, notably in the works of Dostoyevsky, Tolstoy and Chekhov. In the 20th century, suffering as a mechanism of evil was explored by authors such as Solzhenitsyn in The Gulag Archipelago. A leading Russian literary critic of the 20th century Viktor Shklovsky, in his book, Zoo, or Letters Not About Love, wrote, "Russian literature has a bad tradition. Russian literature is devoted to the description of unsuccessful love affairs."